1. Field of the Invention
The present invention relates to an electrophotographic image forming apparatus and, in particular, to an image forming apparatus equipped with a cleaning blade.
2. Description of the Related Art
Conventionally, in an electrophotographic image forming apparatus, for example, an image bearing member bears a toner image thereon. The toner image on the image bearing member is eventually transferred and fixed to a recording material (e.g., recording paper and overhead projector (OHP) sheet) to be discharged from the image forming apparatus. The toner image on the image bearing member can be transferred to a recording material by a direct transfer method in which a toner image formed on a photosensitive member is directly transferred to the recording material. The transfer can be alternatively performed by an intermediate transfer method in which a toner image on a photosensitive member is first transferred to an intermediate transfer member and then a toner image on the intermediate transfer member is transferred to a recording material.
After an image bearing member such as the photosensitive member and the intermediate transfer member bears a toner image to transfer it to a material where the image is to be fixed, a certain amount of residual toner is left on the surface of the image bearing member without transfer. The residual toner requires cleaning of the surface of the image bearing member for preparation of subsequent image formation. A cleaning blade method has been widely used to remove the residual toner by placing a cleaning blade in contact with the surface of the image bearing member.
If the contact between the cleaning blade and the surface of the image bearing member causes too much friction, the contacting portion of the cleaning blade with the image bearing member may be bent over. Even if the contact portion is not bent, the surface of the image bearing member may be scraped off or scratched by the cleaning blade, leading to poor quality of resultant images. To avoid these damages, Japanese Patent Application Laid-Open No. 2007-241114 discusses a structure in which a lubricant is applied to an image bearing member to decrease surface energy of an image bearing member, resulting in a decrease in friction force between the surface of the image bearing member and a cleaning blade.
Japanese Patent Application Laid-Open No. 2004-334092 also discusses a structure with a cleaning blade and an elastic roller as a toner removing member to provide a long-term cleaning performance for toners including a polymerized toner. The cleaning blade is kept in contact with a photosensitive member drum, and the elastic roller is located upstream of the cleaning blade. A lubricant applying unit configured to apply a lubricant to the image bearing member is installed between the blade and the roller.
Unfortunately, such a structure where the lubricant applying unit configured to apply a lubricant to the image bearing member is placed at a distance from the cleaning blade requires a large space for the installation, which increases the size of the apparatus. On the contrary, a structure where a lubricant applying unit is placed close to a cleaning blade to avoid an increase in size of an apparatus may cause a problem that residues such as residual transfer toner and paper powder removed from the image bearing member by the cleaning blade fall and accumulate onto the lubricant applying unit. Any residue such as the toner fallen and accumulated onto the lubricant applying unit precludes an appropriate amount of application of a lubricant onto the image bearing member, which may cause poor or uneven application of the lubricant. Such application in turn may lead to cleaning defects such as bending or chattering of the cleaning blade.
Japanese Patent Application Laid-Open No. 2004-4504 discusses a structure which further includes a cleaning member to remove residues such that the residues such as residual transfer toner and paper powder removed from an image bearing member by a cleaning blade do not fall or accumulate onto a lubricant applying unit. The lubricant applying unit drops not only the toner removed by the cleaning member but a lubricant scraped off by the lubricant applying unit. This requires a conveying member in the structure to convey these residues. The removed toner and the lubricant are individually produced at different positions in a circumferential direction of the lubricant applying unit. Therefore, the position of the conveying member often causes a trouble in conveying one of the toner and the lubricant, or requires another member to convey both of the removed toner and lubricant.